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7. Stewart Island Granite

Updated: Sep 29, 2020

Based on 'Rock glazes of NZ'

Minna Bondy

Sample 15: Pink Granite, Stewart Island

A light colour rock made up of relatively large (up to 1/2") crystals, pink feldspar quartz and mica are all visible in the specimen. Common in parts of Nelson and Westland e.g., Buller Gorge, various parts of Fiordland and Stewart Island. (Granite has a similar chemical composition to rhyolite and obsidian.)

Using Bondy's book as a field guide has me constantly querying her process. Her daughter Ann spoke of family holidays with her mother collecting rocks in the V.W. Beetle.

Were the trips planned in advance? and if so based on what?

There is a lot of rock down this way and not all of it igneous, which was her main interest for glazes. Did she know the rocks she needed and saught them out, mapping them before starting the journey? or simply collected rocks in areas she stayed, and took them home to be tested?

I'm tending to think based on most of the findings appearing quite obviously at popular tourist locations that she simply gathered rock from places she visited, without necessarily knowing the geology, then testing on her return.

One beach over from Oban is Butterfield Beach and this beautiful outcrop of what looks similar to the pink granite sample collected in Buller Gorge. However online there is very little about 'Pink Granite' referenced on Stewert Island and the locals refer to it as 'rotten rock'. While appearing strong it is well weathered and crumbles easily.

I was adamant not to leave the island without an identified sample and scoured the internet for a Quarry. Stewert Island, however, works on a lot better on local knowledge than google and after a quick chat at the D.O.C. the office I tracked one down and whizzed up Back Rd on a hired electric bike. The quarry is the main supply of most of the gravel for tracks and roads on the island and is predominantly a grey granite.

Colin, a dead ringer for the gold prospector from 'The Ballad of Buster Scruggs' happily dug me a chunk of 'white granite' from a seam. He held his arms out wide and with a glint in his eye while explaining he's 'hoping to find the big one' I don't doubt that is what drives him!

I look forward to getting these samples identified properly and will update these blogs as I do, along with images of the samples once they have been cleaned, tested as glazes.

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